Support stand



FIG. 1 is a left front perspective view of a support stand, showing my new design;

FIG. 2 is a right side-elevational view, the left side being a mirror image thereof;

FIG. 3 is a top-plan view thereof; and

FIG. 4 is a front-elevational view thereof. 

The ornamental design for a support stand, as shown and described. 